Tach is driven off negative side of coil so that would make one think yes it is ignition related. Wouldn't hurt to measure fuel pressure as a sanity check as a plugged fuel tank vent can take run time before it occurs.
If you disconnected the tach at the coil and it made no difference. Try...
Need a t fitting and a fuel pressure gauge generally can rig something out of 3/8 flare fittings with a little creativity
What do the spark plugs look like
Valves are staying open in cylinders 2&3 explosion is backfire or exhaust valve is open when the cylinder fires. Likely the water in the engine means the parts of the engine are rusted like valves
Tear the engine down or at least take the head off and see what you have but if you had water in...
Should be willing to do a compression and or leak down test on it. If compression is ok and it has 10 psi /. 1000 rpm of oil pressure hot you ar good to go.
would look at condtion of exhaust manifolds especially if in salt water, as Bondo stated lack of maintenance is biggest killer…
Take the 350 out of the suburban put marine head gaskets in and brass core plugs. Might need to swap the cam might not. Typically truck cams and marine cams are interchangeable in terms of use. Marine needs idle to 5k power range…
basically strip it to thr long block and swap your marine...
In addition since it takes run time for problem to crop up maybe fuel tank vent is clogged putting tank under vacuum try opening the gas cap when it happens see if it makes a difference
If I continue to have issues have heard short life of SEI impellers might be worth swapping impeller for oem merc impeller which will hold up very well
seriously? guy asked if non trailer tires work, i expressed my experience they do in multiple examples where someone uses their head and doesnt go crazy with miles and speed , And everybody’s grandma comes out of the wood work.
When have I done the smartest thing ? I guess I shouldn’t tell you about the blizzaks I had on a 22 ft sailboat trailer … off a car I no longer owned but same rim size …
Yeah makes no sense to me but u have to destroy the rotor to get it off . I changed my cap and rotor last season after six years -there was a little green corrosion on the brass contacts in the cap. what should’ve been a 10 minute job took a half an hour and required chisel …stupid
Just did mine last weekend if you don't have the tool you it will be more of a PITA. Mine is a GEN 2- had a note in manual about putting the tool in the end of the bellow to just slip it over the bellhousing , then reposition the tool deeper in bellows (3rd bellows serration) to pull it up and...
